Telephone switching apparatus



L. POLINKOWSKY.

TELEPHONE SWITCHING APPARATUS. APPLICATION FILED Nov. II, 1919.

by m Affy L. POLINAAOWSAY.

'TELEPHONE swlTcHlNG APPARATUS.

Q jL-ZQAEFLAcATloN man Nov. 1|. 1919.'

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TELEPHONE SWITCHING APPARATUS.

APPLICATION FILED Nov. II. I9I9.

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titten or ltussiew unt. i lieve L iiigj lppiretus, oi" `wliicli the tollen/*1g is :t lit Lele/er, concise, incl erect sc iption. '.llliispinventon reletesfto ,telephone excliiinge systems `:intl`psrticulerly` to systeii'is involvin machine switching` epperiitus tor `setting up conni-ctions.

Qlflie object ot tliexinvention is to provide tlieelectire switches eiuljiloyecl in systems oit this oliereeter `with improved ineens for test1 incl seizing connecting circuits. H

` fit. teettire ottlie invention istb provision2 iirmitoinetc sel-otite switches totm esti-'intllngg connections to `connecting circui ol: i

ijalurelity of testfterniinels :for ezioli circuit `tt ve `relation :is to `pei-init et tne sei"ure ol lille vcircuits enti to `guard suoli "circuits when busy.`

ittuiitlicr lfeeture relates to the :irl-engelnent olif the testterminitls ot esuli connecting;V circuit `in siicl'r n nienner in "tlie terminal benk that the` "brush ot the selective switolr in moving suoli circuit :tiret en# counters :in stivznice testterulinel iiCln tletiL-xrnlines the busyor .idle condition ol' the circuit, intl later by engegg'ingr zr second` ter Iiiinel causes tlie arrest' ol the switcl'i amil tlie seizure ottlie lesiietl circuit.

"It still turtlier ture reletes to en auw li one ot et plurality of ls ot :i count-l eircuiu being o' `tile line teru'iinels Q stlnnslipriortotlieenr vthe line terminals, permits the o wgement c zicl'iizince otsiiitl selector to the tert.

sciiti circuit, it. iille enti prevei'its tlie siniltir in Telephone tilwitclifl switclies lieve access srrlif 'Y "lf .tte t Vivi in itt tlieright ot the brolien line shown the cletelleclr circuits olftlie group selector in tlie `distant enchengein which tlie test trunl;

terminates. s s

Fig. 2 sl'iowse tinel testing` switch tor `use by the Wire @hiet in ii'ieliinsr rontine tests oit subscribersflines. i

Fig. 3 illustrates et register eontrollingl equipment locetecl et the clistent stehen e togetlieniifitl'i tlio switches shown in li" l :incl 2,.encl srrengetl to be positioned troni the Wire cliie'tls clesk for tlie purpose ot controlling` the selective operations oit ssi siiiitclies.` i

lrietiy stated, `the system in Wliicli this invention iseniboclietlis one employed tor performing `routine tests ot subscribers lines so designed tliettlie Wire chiel' et the central exclningc is enebletl to Control tlier operstion ot selective switches userl lor te yFtinp; purposes in e clistint exchange to select e tlesirecl group ot subscribers lines. lflfzw selected :tlierequirecl group ol? lines tiny linein suoli l@up may be chosen end the usuel routine testilofgoperations performed from tliewirif: olliets clesl. lnssinucli es the group selectors snel tine] testing; switches are not infcontinuel use tor melting suoli rout test-s, it is onlyT necessurjv tlist e liniitecl nu i bei" ot tliese swltcliesbe provided. Ylli-.co

ingly, there may be one linel testing? switch :tor eecli group of subscribers7 lines.

3 Sinceonly one ilnzil tel switch viclecl for 'esco groupot l nel., :in entire level in the group selector,` through "which these tintil switches are obtatinetl1 muy be assigned totlie connecting circuit leerling; to eecl'i ot the tlnel ssifitclies.` "llnit is to stty, iu escl] level ofthe gggroui'i selector shown in lfip;a l., tlieiegeppeers tlie terminals olf s, single oon-A necting` circuit leading; to e tinel test' switch llllliile, es eboie mentioned, cr one linzil switch is provided tor erich ot lines, it is obvious tlilit two or switches inigg'litbe essigijivl to esuli 3.o L). iii which cese the terminals ot es nieny switches as were assigned `to e group ot lines, would e'ppeer in e single level ol? "lie group seleotc ils Will be @clearly un- Clerstootl liereinettcr tlie p Wliicli relates toe` novel testing); err. iuselector siiitclies partcula ble s to systems ot this cliereoterj esent inventi n .j

is possible to devote an entire level in the selector bank to a comparatively few connecting circuits.

1t is believed that a more thorough understanding et the invention is to be had from a detailed description of the operation et the system in which the same is embodied.

Assume that the wire chief in the central exrhange wishes to make a routine test of a group ciI subscribers lines in a distant exchange, to which group, for example, the line 100 belongs. lleirst inserts the plug 200 of his equipment into the jack 201 of trunlr 21h-e212 leading to a irst group selector which has access to the proper final testing switch. lVhen plug 200 is inserted in jack 201,'a circuit is closed from battery over the sleeve of the plug and jack, through the winding of relay 202 to ground. Relay 202 closes a circuit for guard lamp 203 to indi-` cate that this trunk circuit is busy. A circuit is Aalso closed for relay 222 traceable from battery through the winding 'of said relay, contact 223 (1), conductor 211, ring of jack 201 'and plug 200, through the wire chiefs apparatus, tip of jack 200 and plug 201, conductor 212, contact 239 (1) to ground. Relay 222 energizes and closes the following circuit: ground, armature and front contact of relay 222, contact 233 (1), through the right-hand winding of relay 2311, contact 2116 (1), conductor293, contact 368 (1) of sequence switch 350, contact 322 (1) of sequence switch 320, through the left-hand winding of relay 323 to battery and ground.

It may be noted at this point that all sequence switch contacts to the left of the vertical broken line of Fig. 3, are controlled by sequence switch 320, and all contacts to the right of said lineare controlled by sequence switch 350. y

' Relay 23st energizes in the above traced circuit and closes a circuit through its le1t`thand low resistance' winding, and the winding et relay 232 to ground, in parallel with that established through its right-hand winding. Relay 232, thereupon energizes and closes a circuit from battery through the winding or relay 237, contact 236 (1) to ground, at the "liront contact and armature of relay 232. Relay 237 at its front contact completes a circuit or'the left-hand winding of relay 257. Relay 257 in turn closes a circuit from ground over its armature and contact, contact 2410 (1), through the winding of sequence switch 220 to battery and ground. l@equence switch 220 moves out of position 1 and into positi-on3. N hen sequence switch 220 reaches position 2, a circuit is closed 'from battery through resistance 261, contact 228 to 12), winding of relay 231, contact and right-hand armature oi relay 202, armature and Contact oi' relay 204, resistance 205, conductor 2111, to ground. Relay 231 energizes and opens the circuit'ifor relay 273 which would otherwise be closed when sequence switch 220 reaches position Relay 231 and relays 237 and 257 are for the purpose of controlling` release, as will be dcscribed hereinafter.

In position 3 of sequence switch 220, the register controlling mechanism shown in Fig. 3, is associated with the trunk 211-212 by the closure of contacts 2412 and 24:3. The wire chief by depressing key 215 closes :in impulse circuit from his sender 216 through to the stepping relay at the register mechanism. This impulse circuit may be traced 'from battery, through the lett-hand winding of stepping relay 3 5, conductor 217, contact 2&2 (3) contact 211, ring of jack 201, ring of plug 200, through the lower con` tact 01"' key 215, sender 216, upper contact of key 215, tip of plug 200, tip of jack 201, conductor 212, conatct 243 (3), conductor 218, contact and lelithand armature of relay 339, through the right-hand winding of relay 325 to ground. Relay 325 energizes in this circuit.

At the time the above traced circuit was closed Jfor relay 231 in series with the lefthand winding et' relay 323, this latter relay also became energized. The sequence switch 320 is therefore driven from position 1 into position 3, by means of a circuit from battery through the winding oi said sequence switch, right-hand winding of relay 323, front contact and armature of relay 323 to ground. Then the master contact 321 of se`- quence switch 320 closes on leaving position 1, the right-hand winding oi relay 323 is shunted, and when contact 322 opens the circuit through the left-hand winding, of relay 323 is broken, thereby causing the deenergi- Zation of said relay. When sequence switch 320 reaches position 3 and relay 323 releases its armature, a. circuit is closed from battery through contact 327 winding of relay 326, back contact and armature o'l relay 323 to ground. Relay 320 closes a circuit from ground at the armature and iront contact of' stepping relay 325. through the armature and front Contact of relay 320, contact 330 (3) right-hand winding and contact and armature o'l relay 320, contact 323 (3), through the winding ofi the thousands regiser 110, to battery and ground. In parallel to this circuit a circuit is also closed at the same time for the lett-hand winding et relay 329. Relay 329 being differential does not attract its armature when both of these windings energize. The thousands register 110, however, energizes and moves out of position 0. lVhen the master contact 111 of the thousands register closes between position 0 and position 1, the right-hand winding of differential relay 329 is shunted and said relay attracts its armature. Under the control of its master contact, the register 110 advances into position 1.

essere@ Art the tiine sequence switch SSZOreaches position 8, the primary Winding oit the dialing tone co1l324- isclosed in seriesjirith the "interruptor 333 at contact 'lhe Wire chief,y hearing` the chari-icteristic tone in the centrolling.;mechanism.` ln operatingfhis sender Qlfor the lirstseries oit impulses, the first `lnterru"ption ofthe impulse `circuit causesthedeenergization ot stepping relay "closed" tor the register ll() in se lies with right-hand 'irindingot' relay 32%). Register .i manner described.

`isdriyen forward another position.

The left-hand Winding oft diiilerential relay 329 is thereupon opened and this relay releases. Atthetollowing closure oi" the i1npulse circuit, the above `traced circuit is ll() thereupon moves from position ll into position 2, `and relay 329 energizes in the Un the second inter-` ruption ot the line, relay 329 deenergizes7 and at the second closure ot the `line register ll() rlhis procedure continues9 the register il() advancingl one position for eacl'riinpulse sent trom therwire chiets sender.` 'lhe sender 2,16 is so designed that the lastinterruption oifthe line for yeach iinpulsei series is comparatively longer than the `precedinzg;1 interruptions. rit this last comparatively long'interruption the circuit from hattery through the, windings of `relay 334:, Contact 34:2 ack contact and armature of relay 325 to ground is maintained closed toria period sutiicient to e permit the relay 331i to attract its armature.

` This relay, being slow to enervize7 din not operate on each of the` preceding' short interruptions ol the line. Relay 331i; closes a circuit from ground/4 arn'iatu re and contact of said relay, through the right-hand Winding olf relay 328, winding oil sequence switch 320 to battery` and ground to drive sequence switcl'i 320 out ol position Si and into posi-` tion (3L ln leavingl position 3 the master contact short-circuits the right-hand winding' ot relay 323 and the circuit ot relay 3254i heingopened at Contact 342, relay 3522-3 de energizes before sequence switch 320 reaches position.

Un oolningeinto position (3 sequence switch. 320 shifts the control ot the stepping` relay troni the thousands register ll() to the hundreds register 1207 and a circuit is closed troni ground, armature and :front contact vot relay '325, armature and liront contact ot relay 326,` contact ll ot register l l0, ripdit1 hand vv'inding` and contact ol `armature ol vrelay 329a Contact 828 (G), Winding ot reg- `ister l2() to battery and zground. The cu.Ik

cuit ust traced leads through the contact ll ot the thousands register lll), either closed in position 9 or position 0? as Willhe incre fully explained hereinafter. he register 120 energizing in this circuit 'moves 'from po# sition 0 yinto` position l, in the manner dey trent contact oit rela scriled iur connection with the thousands pulse circuit ttor the second series ot` iinpulses, the register 120 is advanced through one position. .nt the last interruption oil" the impulse c. cuit sloW-to-energine relay 331i, attraotsit armature and `closes a circuit as above desc. out ol po ition (3 and into position l0.

llVlien-'tliie line circuit as tin closes a circuit is completed troni ground? armature and ifi-ont contact f( and aii'inature ol relay 525), contact 335 (i3) winding oit a units rc" 1 iter le() to hattery and Iground. ldlheiii the units register la() has heen positioned in accordance 'with the nurnher ol impulses in the linal series, relay 381iagainenergized and sequence switch 3Q() is' driven gironi position. l 21S into posi tion 16.

Betere proceeding' :tui-ther with the de scription ot the operation,` a loriei'` explanation `will he given oi the type oi register controllingo]` niechanisin used in this system. lhe reigisterin controlling incch incorn- A an oi? Jtnicnce"sei n 0 controlling positions,` one for each d Dit. A u isters are driven under the control of the impulse sender troni position Oto a position correspendingl to the nuniher of impulses sont. fiiaving; heen in these positions,` they are then driven through their remaining' positions to position 0 tor controlling the selective increments on the switches. ltzwill he seen that the nuniher ot positions through `Wl1ich each ot the registers are movedy duringv their return to normal `is the complement oit ithe nuniher oit impulses sent troni the impulse sender in setting the reg;-L

istcrs. lt therefore heroines" necessary to design the senderssothat each irnpulse series sent contains a nuniher of impulses equal tothe `coinpleiuent ot the actual digit concerned.

niechar sin shown in l? 3 is located is assumed to have va capacity ot 2,000 lines. Co sequently the thousands register ll() will always he `s in one or the other ot its two mntrollingg positions 9 and 0. 'lhat is to sayv it the desired line is in the even or zero` ster i3() isinoyed through one posi- Upon being positioned, theseA register 110. it cach interruption of the iin- .ihed to i drive serpience switch 3Q() lesy lith

in. the ilfiresent system the distant exchange in which the control]ing` ldd longs to the odd thousand, register 110 will l beset in position 9, the' complement of the contact or relay 35i',

vsequence switch out or position 3 into digit 1. v-

Whenthe i'irst two registers 110 and 120 have been positioned, which corresponds to sequence switch ltlnioving from position 5 to position 10, thousands and hundreds selection talres place without waiting for the remaining registers to be set. ln position 7 of sequence switch 320 a circuit` is completed troni ground, contact 338, contract 113 oic register' 110, contact 2352 (l), win'dingot sequence switch 350 Vto battery and ground. .Sequence switch 350 moves out et position 'l and into position 3. ln this position the fundamental circuit is established preparatory to controlling the brush tripping operation at thegroup selector. This circuit may he traced from battery through the winding oit relay 222, contact 9&7 (3), conductor 296, winding ot' stepping relay 855, armature and to ground, at contact 356 Relay 222 energizes and closes a circuit from ground over its armature and At'ront contact, contact 227 (3), winding of seguence switch 220 to battery to drive said position 4. ln position t of sequence switch 220,' the brush tripping poner infonet E is energized in a circuit from batteryy through the winding thereof, Contact 2119 to ground, at'the Yliront contact and armature oi relay 222, The brush tripping spindle is thereby rotated'to select the particular' vone ot a plurality of sets of brushes that has access to the desired level ot terminals in the selector banlr. As each brush tripping position is passed by the tripping spincile, the interrupter contact 250 closes a circuit tor relay 222 including contact EL3 (4l) in yshunt of the stepping relay 355 in the fundamental circuit. At the lirst closure oi. the contact 250, relay deenergizes and the following circuit is completed; ground. contact 369 armature and contact of vrelay 355, lett-hand winding and contact and armature of relay 359, contact 361 contact- 122, winding or' thehundreds register 120 to battery and ground. In parallel to this circuit, a circuit is also closed through theA righthand winding of relay 359. Relay 359 is made differential and therefore does not attract its armature when both oft its windings are energized. The hundreds register 120, however, energizes and moves from the position to which it was adjusted to the nenty suceeding position. In

,the saine manner as described in connection with the operation oi the differential relay 39.9, the relay 359 is permitted to energize when the master contact of the register is closed in passing 'from one position to another. Asithe brush tri onine' s indle reaches its first tripping position, contact Q50 is opened. The stepping relay 359 energizcs to permit the deenergization ol the diil'erentiai relay This operation proceeds until the hundreds register reaches position l). iis soon alter register' l2() reaches posi` tion tl, as the interrupter contact 25? again closes, and relay deenergizes, a circuit is closed from battery through the winding oi" sequence switch 350, contact 363 (3), contact 114i (assuming register 110 to be standlng in position U, Contact (l), contact tzal (il), contact 361 (23), armature und contact of left-hand winding ol rela y 2.351), contact and armature of relay 359, to ground, at contact ln parallel to this circuit a circuit is also completed lor the energization of relay 35T. rllhe relay 357 opens the fundamental circuit to guard against further operation ofthe tripping spindle, and sequence switch 350 energizes and moves into position 4. When the tripping spindle interrupter contact 250 again opens relay dcenergizes, since the fundamental circuit is new broken at the register controlling mechanism. llelay 222 closes a circuit from ground over its armature and baci; Contact, contact winding o t sequence switch 220 to battery and ground to drive such sequence switch into position 5.

The selected set of brushes, as ttor cxamp le, the brushes 251, and i253, are now ready to be driven orer the terminal level contain ing the terminals l"l'5, 76, 1188 and 11.85) of tl e connecting circuit leading to the proper final selector. The connecting circuit leading to the linal selector switch is provided in the terminal bank el? the group selector,`

with the two line terminals 4:75 and e176, and also with two 'terminals 8S and +1181) in the test row. The terminal 45S is so arranged in the level that the test brush 252 engages the same, bollire the line brushes and 9?) have reached terminals 2:75 and alv. The terminal 89 is so arranged that the test brush Q52 makes engagement therewith simultaneously with the engagement; of brushes 251 and with terminals i-T5 and lr6. lit the iinal testing switch is idle, the test brush Q52 oi' the group selector passes over terminal 18S and comes to rest ot terminal 489, permitting the seizure et the connecting circuit leading to said final switch. it, however, the linal switch is busy at the time test brush 252 reaches terminal 488, a busy condition on this terminal will cause the group selector to stop before its brushes have reached terminals 4575, 1176 and The testing operation olf the group selector is eilected by iueans ot a circuit from battery through 'the winding oi" brush carriage power magnet :241, conta-ct 254: (5), to ground at the contact and armature of relay The brush carriage rotates and advances the lUll lil(

test brush first into engagement with .terininal`480- A circuit is then completed from battery over terminal 480, `brush 252, contact 246, righthand winding of relay 234 to ground at contact"239- `Relay 234 energizes and closes a circuit through its left-hand winding, and the winding of i ea brush `carriage is so adjusted with respect to the speed of sequence switch`220, that the test brush 252 reaches the terminal 488 prior to the arrival of sequence switch 220 in position 11. Assuming the final test switch to beidle, no busy condition will be found on the test terminal 488 by the brush 252, and sequence switch 220 will come to rest* in position 11; The brush carriage, therefore,

-continues to rotate by means of the circuit `traced and the brushes 251, 253 and 252 are advanced into engagement respectively with terminals 475, 476 and 489.

Upon test brush making contact with terminal 489, a circuit is established from battery, through resistance 442, contact 441 (1) `of sequcnceswitch 450, terminal 489, brush 252, contact 246 (11), right-hand winding` of relay 234 to ground, at contact Relay 234 energizes and closes a paral lelcircuit through its left-hand winding and the winding: of relay 232 to ground at contact 239,` lRelay 232 energizing, opens the power `circuit of magnet` 231 and closes a circuit from battery, through the winding of` holding magnet 245 to ground at the front contact and armature of relay 232:

l-lolding magnet 245 operates to arrest the brush carriage with the brushes accurately centered upon the terminals. 475, 476 and` 489,` Relay 232 also closes a. circuit from `ground over its armature and front contact, contact 229 (11), winding of sequence switch 22() to battery and `ground. Sequence switch 220 advances'froiu position 11 into position 12. `With sequencey switch 220 in position 12, relay7 is maintained energized in a circuit including contact 247 (12)",

conductor contact 368` (1 to `9:) back contact and rightehand armature of relay 339 to ground at contact 340. rlihe closure vof sequence switch contacts 255 and 25,6 in

position 12 now ext-ends the fundamental. ein

cuit from the register controlling mechanism.

through tothe final testinaswitch. This,

circuit may traced from `batte-ry through the winding of relay 452, contact 444 (1), contact 476, brush 253, contact 256 (12), conductor 296, winding of stepping relay 355, armature and contact of relay 357, contact 356 (5), conductor 297, Contact 255 (12), brush 251, terminal 475 to ground, at contact 445. It will be noted that thesequence switch 350 advances from position 4 into position 5 to close the fundamental circuit at contact 356, as soon as the units register has beenpositioned. lThe circuit for moving sequence switch 350 into position 5 may be` traced from battery, through the winding of said sequence switch contact 363 (4)" to ground at contact 341 (16).

The relay 452 energizes and completes a circuit from ground, contact 466 (1), armature and front contact of relay 452, contact 446 `(1), through the winding of sequencel switch `450 to battery and ground, moving sequence switch 450 out of position 1 and into position 2. In position 2, sequence switch 450 closes a circuit from battery through the windings of relays 484 and 483, contact 443 (2), terminal 489, test brush 252, contact 246 (12), right-hand winding of relay 234 to ground at contact 239 (12). litelay 234 energizes and `closes through its lefthand winding and the winding oit relay 232, a circuit in parallel with the one just traced.

Relay 484 energizes and prevents sequence switch 450 from moving out of position 2 by means of a circuit which would otherwise be closed over contact 467 (2). The brush tripping spindle is now `rotated to select the proper set of brushes as determined by the position of the tens register 130. The eircuit for the tripping spindle magnet 448 may be traced from battery through the winding of saidinagnet, contact 447 (2), front contact and armature of relay 452 to ground of contact 466. For each brush tripping position passed over a circuit is closed for relay 452, over contact 449 (2), and interrupter brush 455 in shunt of the stepping relay 355 in the fundamental circuit. The first shunting of relay 355 causes this relay to deenergize and close the following circuit; ground, contact 369 (5), armature and contact of re- 355, left-hand winding and contact and armature of relay 359, contact 367 (5), contact 132, winding of tens register 130 to battery and` ground. ldegister 130 advances in the manner described from the position to contat 134i (0), contact 367 armature and contact and lett-hand winding of relay 359, contact and armature of relay S55 to ground at contact 369 In parallel. to this circuit a circuit is also closed for relay 357. The relay 357 maintains the fundamental circuit open while sequence switch 820 energia-cs and advances 'from position 5 into position 7. As soon as the interrupter 155 again opens atter the'tundamental circuit has been severedvat the register controlling' mechanism, the relay 452 deenergizes. A. circuit is then closed trom battery through the winding; oi sequence switch 450, contact 4.46 back contact and armature ot relay to ground at contact 166 (2), sequence switch L50' advances from position 2, into position 3.

As soon as contact 367 is opened, as sequence switch O'movesout of position 5,

' relay 357 deenergizcs and closes the fundamental circuit at the register controlling mechanism. Relays 152 and therefore immediately become energized. The operation of relay 152 closes a circuit vtrom battery through the windingot sequence switch 4:50, contact e116 (3), front contact and armature ot relay 152 to ground at contact 466 lSequence switch itlmoyes out ot position 3 and into position 11. In this position the brush carriage of the final testing switch carrying brushes 110, 411 and 412 is rotated by means ot the power magnet 4:61. The circuit ol" magnet 161 may be traced from battery, through the windingthereot, contact 456 (et), front contact and armature ot relay 152 to ground at contact 4:66.01) as the brushes approach the tirst set oit terminals in the leyel the interrupter contact 415i' closes a circuit tor relay A'152 includin,.fl contact fr...) (l1), in shrnt ot the steppingv relay 355 in the fundamemal circuit. The deenernjization ot relay 355 causes afcircuit to be closed trom ground, over contact 369 (7), armature and contact or relay 355, lett-hemd .winding and contact and armature of relay 359, contact i567 (7), contact 1112, winding oit' the units register 140 to battery and ground. The

units register 1-10 advancesthrough one :eo-

sition in the well-known manner. Villien the units register 14iO'later reaches position 0, the brushes 410, 411 and 412 are about to malte engagfement withV terminals ot the desired subscribei"s line 1100. At this time the interrupter contact 457' is closed and relay 355 is deenergized. Hence a circuit is established from battery through the windingof sequence switch 550, contact 352 (7), contact 144 to 0, baclr contact and armature of relay .S7-fi, contact 1113 (O), contact 367y (7), armature and contact and lett-hand Windingv ot relay 359, contact and armature oit relay 355 to ground ot contact 369 A parallel circuit is also `for the relayv? which operates to hold the fundamental circuit open.

The sequence switch onergrizes and advances from position T into position 1S. On reaching` position 19, thc sequence switch H5() is immediately advanced into .its normal position l., by means oit a circuit trom battery through the winding oit said sequence switch contact 352 (1S), back contact and armature of relay 326, contact 336 (1S) to ground. lVhen the brushes L110, all and i12 are accurately centered on the terminal o'l. the desired line the interruptor Contact T opens and relay fi-52 deenere'ires. fr circuit is thereupon closed from battery through the winding); ot sequence switch 450, contact Al-l-( (i), back contact and arnmtures ot relay A152 to `ground at contact L1613 (i). Sequence switch 4:50 moves out of position 1 and into position 9.

Thesequence switch 350 on leaving; position 9 opens at its contact 36S the circuit which up to this time has been maintaining; the energization ot relay 222. The relay 222 by deenergizing closes a circuit lrom `:freund orer its armature and back contact and contact 229 tor dririm; sequent-0 switch 220 into position 141-. in. lez ring position l2, sequence switch contacts 242 and 2123 open the circuit of the stepping` relay S25. This relay deenergizes and causes the restoration et the register controllingmechanism. The I deenergization ol rela., 325 closes a circuit from ground. over its armature and back Contact, contact "18 (1G) wimlinpj o l sequence switch 320 battery and grouinl. Sequence switch advances into position 17. In this position, relay 5323 is enei ,Y 'Zed by means or", a circuit Yfreir.. battery, through the lc'l'thand winding` ot relay S23. contact (1.7)

to ground at contact 169 (l). 'elay 323 rcnit trein lrround through ilsv closes a armature and trout contact and right-hand windiiilg, and the winding; off sequence switch 320 to battery and `ground. Sequenro switch 520 moves out o'l. position 1T and into position l. The master contact 321 o'f sequence switch 320 shunts the winding' ot relay 323, so that this relay is permitted to dceneririzc upon the opening ot contact 3-2. The ren'- ister mechanism is fiow completely restored to its normal position.

lVhen sequence switch 220 leaves position 12, the circuit olli relay 2551 is opened at corr tact 22S In position 13, this relay is maintained energized by means ot a secondary circuit from battery through resistance 262, and contact 2:26 (13). itis sequence switch 214i leaves position 11.2. the hei-cintofore traced circuit for relays 18st and. 483 in series with relays 223-1- and 232, was opened at Contact 2&6 (12). Relays 231 and 232 deenergized, but relays iS-1 and 189 are maintained energized in the 'following circuit in position 11- olf sequence switch 220: battery through the windings ot relays L8-.lf and 11:83, Contact 4&3 (10), terminal +189, brush 252,

lftl

,neetinw y over Vfrequence switch contacts 255 and 250 ifiea eontactll (142)., Winding oli' relay 23,1.,conductor` 2li-3, Contact andxritht-hand armature oirelay 2,7arn1atme and contact of relay 204;, resistance 9:05.. conductor 2141.1 to ground. rlie relays ane t heingsensitive energize in this-circuit, arliereastlie relay i553 heinginar" al, `Will not operate in series with the reeietance 230151 The toet trunk 2li, Q Qleaoinpj from the 'wire chiets `deslr` is noir conne ted directly through to the conu "ruitoii the test switch in Fig. 2,

closed in positionlft." The relay 4:52 again energiaes in series with the trunk Qlland 2l?. and closes a circuit trein .Ground over` l l l r contact 466 (9), arniature and ifront contact oiirelayl 452, contact i450 (9),1 `Winding ot" sequence switch i501toloattery and ground to drive Sequence switch L50 into` position l0. The'apparatus remains in this condition untilthe Wirefchieis readyto `proceed with `the.(testingv or the selected line; l llVhen he releases `lrey :for this purpose, the relay 452 deenergines anda `circuit is established roniground over Contact 406 (l),`arni`ay tureand hack contact oiqrelay to2, contact y se 41%,"(10), Windin oi? eequenceswitcli Zl5() to hatery `and (ground. Sequence switch ll nieves out of position ,l0 and into position 1l in which *positron the `testing circuit 1s' extended to the hrushes `allland Llll by the closure oi Contact 41.45 and elle. After hav- 14.0.. to select .the nen and` armature ot relay 481i to ground. Relay relayc. 1 Relay 209 is made slow to operate et. y

ene

ing` performed the necessary test of the line 1,110.0,"tlie Wire chief .may desire to test other lines in` thiefgroupfin the saine manner. For l this purpose a prorieion is `made 'whereby he mayadyance the final testing switch step floyfstep into engagement with the Successive lines to the `group `Without .the necessity olf resetting,` the register controlling` rnechaniem group.` For] example, lie depresses a lrey 20B, individual to the test `trunk ll-Qaud also a comroon key E207. y r'llheclosure of these keys complete ay circuit for relays E204 and `'llie vrelay `204iiinrnediately energizes and opens thecircuit` ol` relays i231 and 4:84@

which thereupon `release their` armatures. The'. deenerfrizatlon of `relaylla results in the closureot acircult` from battery through the Winding oil' relay 86, left-hand Windingw oiffrelay 485., contact 46?(11), `haci: contact ll05"lenergiaes andloelrs up over its right`- handiwinding 1n series with the `uunding` ot so thatit does notcloeeits contacts until a predetermined interval after they operation oil relay 201i.,` lllhen relay Q09. attracts its4 armature relayOis slfiunterlwout` and de- 'r/lee to again close the circuit oit relaye i231 and i-.84., llelay. iS/ lf new` completes a circuit from ground over its armature and `.succeeding line in Athe ,eee i y 1 sequence'switch 450 to hatteryzmd ground. deqiicnce switch 50 nieves into position l2, i Where a circuit completed tor the brush Y hie circuit f fron'i battery through the Winding ot carriage power magnet fl. leads said ni cnet, Contact i150 rature of relay iff iront contact .i liront rontact and arinautre oi relay 4181i.' The brush cari' fe rotates" and upon the closureoifj Contact 4 il", a. substitute circuit is closed lor relay to2, over eequenceswitch contact L49 (la) in shunt oit the circuit tlirougl' y v ,t-hand Winding ot relay 405.. ,slelav Sotheretore deenera'iaes and opens m 5 the originalenergizing circuit of relay 4:52, so `this relay deenergizesJ as soon ae `the hrusoes 1 -10,4111 and 4:12 reach theneirt `set oi" line terminals and interrupter contact opene.` rllhe deenergiration oi' relay 459/ epenathe circuit of the power magnet 4:61

ingr niagnet 4105, `a circuit is also closed tor relay 4:82, over sequence switch contact L50 attractie its armatiufe and closes a circuit for a second @leute-energize relay 4:01.@ l llhen relay. 4:81 hecornee energized `it .opens the cir-` ritterV this cuit o'lfrthe holdingi .a net 465. line has heen tested. hj the Wire chieti, the tical testing switch may 'he `adVancerl to the terminals oi' the nenteuceeedingline in the nianner alreadydescribed.` Each tine-.e the relay 4:84: i yleases armature, it closes, ae

above noted, circuit tor relay i-0G. Relay to ground, at the Whiclicrow to energize,`

4:80 in turn completes a circuit for relay 4187; l

fl'his latter` relay when `ene iced, closes a cirr cult ttor restorii g the eequence Switch 450.

Relays and 4.o?, however, are made slow i to energize and do not have euiieien time to operate, While relay l0/i is deener ing' 'the operation of the `Final test in; switch from one set of terminals to another. ln a similar manner, the relay Q31 closes a circuit iter relay 2537 which in turn close. circuit :tor relay 9,571] lielay 257 hy energizing, completes a circuit troni ground over its armature and nach contac 940 (1%),tliiougli iteplelit-lianil uindingand the 'winding oitl sequence si tch, 000 to `battery. This circuit reeults in driyii the sequence switch 220 The relaiV ff'land Q37, sleeT to opera1 ,ll not. have tiine to. close in eucceseion during; 'the brief `interyale that relay 251i ie deenerrrized in the operation of 1 adrancrlng` 'the inal testingswitch ni one eet oir' terminals te the next.

lie

lil-eti If the wire chief has completed the test-- ing of the subscribers lines, and wishes to releasetlie apparatus, he removes the plug EEOO'trom the test jaclr 201. The relay 202 therefore releases rits armature and permanently-opens the circuit et relays 231 and 484;. `Relay 231 causes the successive energization ot relays 237 and 257, and sequence vthrouh the windineo se uence switch 226 Contact 229l (17v to 18), trent contact and armature of relay 232 to ground. equenee switch 220 thereupon moves into position 1.

The permanent deenergization et relay 184 permits slow-to-energize relays 486 and 487 to attract their armatures as above described. Relay 487 closes the circuit for driving sequence switch i90 out of position 12 andinto'position' 17. On leaving position 12 the circuit et' relay 486 is opened at contact 467, relay e186 immediately deenergizes and causes the deenergization ol rela, 4187 so that sequence switch i150 comes to when it reaches position 17. The brush carriage of the final selector-is now restored to normal position by means ot a circuit from battery through the winding` oih4 power magnet 161, yContact 156 (17), baci; contact and armature of relay 152 to ground at contact 466 (17 On 'reaching its normal position fthe interrupter brush 457 closes a circuit from battery through the winding ol sequence 'switcli'4;50, contact L141-6 (17).. front contact and armatures of relay' to ground at ycontact 466 (17). Sequence switch 150 thereupon moves out of position 17 and into `its normal position 1.

yAssume new that the linal test sutoh shown in Fig. Qlfis already engaged by some other group selector at the time the sele ter shown, attempts to make connection therewith. In this case the sequence switch 156 will be in some position other than position l., and battery will be suppli to 'the test terminal 488 over Contact l-il (2 to 1). Therefore upon the test brush 252 engaging in the terminal 188, the following circuit 's closed: battery through resistance ill-2, contact/1&1 (2 to r18), terminal 488, b; ish 252, Contact 9&6, through thel right-hand winding oi relay 231i to ground at contact it will be noted that while the sequence switch 220 does not reach position 11 until after the test brush 252 has made engagement with the test terminal 488, said sequence switch will have reached position 8 by the time the test brush engages terminal 488. 'lherebre the contr-ct 246 will hare been closed by the time the terminal 188 is reached, and relay 284 energizes in the circuit above traced. lle/lay 234C closes a circuit through its left-hand winding, and the winding of relay 82 in parallel to the circuit traced through the right-hand winding of relay 23e. Relay i232 energixes and closes a circuit from battery through the winding oi" relay 22e, contact 244 (7 to 10), trout contact and armature ot relay 2232 to ground. elay Q t attracts its armature and loclis up over a circuit including the back contact and mature et relay Sequence switch 220, stead oit now stopping in position 11 to permit the advance of the group selector to the terminals 175, ll76 and I189, continues to moreover positions 12 and 14, and comes to est in position 16. The circuit 'from driving sequence switch 220 in position 16 may be traced trom battery through the winding ot said sequence switch contact 227 (7 to 1e), contact and lett-hand armature ot relay to ground. A busy condition encountered on the test terminal A488 thus serves to arrest the brush carriage ol2 the group selector before the same can advance into engagement with the terminals et the connect-iin)` circuit leading to the final test switch. In position 16 of the sequence switch :2:20, a busy tone 'lrom the machine Q66 is transmitted in the well-known manner to the wire chiets apparatus due to the closure of contacts 242 and 2413. The wire chiot herring this busy tone knows that the final test switch is engaged and removes the plug 200 'from jack 201. Release ot the group selector now takes place in a manner similar to that previously described.

lVhat is claimed is:

1. in a telephone system, a connecting circuit, a selective switch for extending telephone connections over said circuit. a plurality oil terminals individual to said circuit in said switch, a brush for said switch, means for movingF said brush successively into engagement with said terminals, and means rendered elllective by the engagement oi"A said brush with said terminals ili'or testing and seizing the connecting circuit.

ln a teleiihone system. a connecting circuit, a selective switch for extending lelephone connections over said circuit. a plurality of terminals individual to said circuit in said switch, a brush tor said switch, means for moving said brush successively into engagement with said terminals. means rendered etlicctii/'e by the engagement of said brush with one of said terminals tor testing the condition ot the connecting circuit, and means responsive to the engagement of said iasaaes brush with another of said terminals for seizing said connecting circuit. y

3. ln a telephone system, a connecting cir- .i cuit, a selective switch for extendingtele- `phone connections over said circuit, a pair of terminals individual to said circuit in said switch, a brush for said switch,-means for moving said brush successively into engagement with said terminals, means rendered effective by the engagement of said brush with one of said terminals for testing the condition `of the connecting circuit, and means responsive to the engagement of said brush with the second of said terminals f'or seizing the connecting circuit.`

Ll. ln a telephone system, a selective switch, a connecting circuit, a plurality of terminals individual to said circuit in said switch, a brush for said ranged to make contact with said terminals, means for driving" saidbrush over one of said terminals to test the condition of the connecting circuit, and means operated upon the engagement of said brush with another of said terminals for stopping the selective switch to seize said connecting circuit. f

5. In a telephone system, a selective switch, a connecting circuit, a plurality of terminals in said switch, a brush for said switch arranged to make contact with said terminals, means for driving said brush over one of said terminals to test the condition of the connecting circuit, means operated upon the engagement of said brush with another of said terminals for `stopping the selective switch to seize said connecting circuit, and means for placing a lousy condition on the first of said terminals.

6. In a telephone system, a selective switch, a connecting circuit appearing in said switch, means for driving said switch into engagement with said circuit, a plu rality of terminals for said circuit, a brush f'or said switch arranged to engage successively said terminals, means effective upon the engagement of said brush with one oit switch arsaid terminals for testing the condition of the connecting circuit, means responsive to the engagement of said brush with another of saidterminals for stopping the selective switch in engagementv with the connecting circuit, and means for stopping said selec tive switch before it engages the connecting circuit if said connecting circuit is lousy.

7. In a telephone system, a selective switch, a connecting circuit appearing in said switch, means for driving said switch into engagement` with said circuit, a plurality of terminals for said circuit, a brush for said switch arranged to engage Vsuccessively said terminals, means effective upon the engagement of said brush with one of said terminals for testing the condition of the connecting circuit, means responsive to the engagement of said brush with another of said terminals for stopping the selective switchl in engagement with the connecting circuit, and means responsive to the engagement of said brush with the first of said terminals for stopping the selective switch hefore it engages the connecting circuit, if said connecting circuit is busy.

8. lln a telephone system, a selective switch, a connecting circuit appearing in said switch, means for driving said switch into engagement with said circuit, a pair of terminals for said circuit, a brush for said switch arranged to engage successively said terminals, means effective upon the engagement of said brush with the first of said terminals for testing the condition of the connecting circuit, means responsiveto the engagement of said brush with the second of said terminals for stopping the selective switch in engagement with the connecting circuit, `and means for stopping said selective switch before it engages said second terminal, if said connecting circuit is busy. ln witness whereof, I hereunto subscribe my name this 13th day of October, A. D. 1919.

Lira'rommrowsirr. 

